The use of communication systems having wireless mobile communication units has become widespread. Wireless communication systems that operate within a cell or coverage area provide several important advantages over conventional wired systems. For example, wireless communication users can communicate in locations where wired service is not available or feasible, such as remote or rugged locations. Additionally, wireless communication users within the cell have much more mobility because the units do not have to be connected to a fixed wired network. These and other favorable characteristics make wireless communications ideally suited for personal, business, military, search and rescue, law enforcement, water vehicle, and other field related applications.
Common approaches to providing wireless communication systems include two-way radio systems and cellular systems. Despite the benefits of these approaches, they have several drawbacks. First, the cell size or range of units within these systems depends, at least in part, upon the power provided to the units. Typically, disposable or re-chargeable batteries are incorporated into wireless communication devices to provide operating power to the devices. The batteries can provide different amounts of power to units, depending on the size and/or weight of the batteries. For instance, a small battery may provide on the order of 100 milliwatts to a unit, and may be compact and lightweight enough to be incorporated into a cellular telephone. However, such a small battery provides only enough power to facilitate a range of a few miles, and only for a few hours.
It is for this reason that a plurality of fixed base stations or towers need to be constructed within a couple of miles of one another to make cellular systems effective. The towers define multiple cells and serve to, among other things, receive the weak signals transmitted by cellular telephones, so as to achieve usable range even as the cell phones themselves achieve only a short range. The towers also extend the operating life of the cell phone batteries, by enabling the units to transmit at a low power level. However, such towers are expensive, and take a substantial amount of time to construct. The cost of building such base stations is not warranted in some instances, such as in extremely remote areas. And, it may not be possible or desirable to build towers at other locations, such as on battlefields or in war zones, where the communication coverage area or cell needs to remain mobile, and the towers themselves would represent vulnerable targets for the enemy.
Two-way (e.g., peer-to-peer) radio systems do not need to be connected to a fixed network, an advantage is some operating scenarios, as compared to cellular systems. Larger batteries (e.g., on the order of two to twenty-five watts) are often utilized in two-way radios to expand the range of a system without the use of towers. However, even the power of the larger batteries is quickly consumed if the two-way radios are used often, or over a long range. In addition to battery issues, two-way radio systems can be limited to line-of-sight type radio systems that have constraints, such as antenna size and/or line-of-sight constraints. Military line-of-sight type radios are typically VHF (Very High Frequency) or UHF (Ultra High Frequency) radios that broadcast in frequencies from about 30 MHZ to 300 MHZ, and have effective ranges of about 5 to 25 miles, based on RF power, the antenna/mast height used with the radio, and other factors. These VHF/UHF radio types can have their coverage obscured by mountains or other line-of-sight obstructions, but are used because these radio bands can be highly reliable. Other radio types can at times provide operate beyond-line-of-sight service, for example, HF (High Frequency) radios. HF radios broadcast in frequency ranges from about 1 MHZ to about 20 MHZ, and can at times achieve with much longer ranges than VHF/UHF radios. However, the HF radio broadcasts are much less reliable than the VHF/UHF radio broadcasts types.
Existing communications systems (voice, data, etc.) to and from dismounted individual users on a battlefield have severe technical limitations that impede and degrade tactical operations in significant ways. Existing problems areas include battery life, range, relaying, safety, weight, complexity of operation, setup and configuration time, and missing functionality. Similar problems plague electronic communications to small mobile teams in other domains, e.g., search-and-rescue teams, law enforcement agents in the field, etc. The fundamental problem with current implementations involves limitations in the present art of how electronic communications (e.g., voice, data, imagery) is implemented for such teams. Weight, size, and battery life are significant design drivers for how a radio carried by an individual (e.g., in the hand, in a backpack, or attached to the body by some other means such as slung from the belt) is designed and implemented. Most current art uses single-channel radios with “push-to-talk” channel access for these types of applications. These work fairly well in smooth terrain for communications within the team, but work poorly within the team in rugged terrain, and work poorly in any terrain at connecting the team to a distant “home base”. They also are very limited in terms of communication access (e.g., cannot talk to other users on different frequencies, hop-sets, cryptographic variables, etc.).
The selection of the single-channel push-to-talk radio drives a communications range requirement, which drives an RF power requirement, which drives battery utilization. The result is that the weight of the batteries required to operate for even 24 hours usually exceeds the weight of the radios. In the military, ideally an individual would go to the field with batteries sufficient for at least 72 hours of non-stop operation. That is simply not possible when single-channel push-to-talk radios are used. Another related problem is antennas. The frequency bands of these sort of single-channel push-to-talk radios require masts and antennas that are a few feet long. This is awkward and ungainly for individual use. A secondary problem with current implementations involves poor selection of functionality for the data/information portion of the capability. Present implementations tend to be too complex, present too much low-value information, require too much manual action (e.g., typing) on the part of the mobile user, and require the user to hold a computer in his hands, even to accomplish emergency or other actions where a short response-time is required. Many current systems place equipment on the soldier's helmet, and dangle eye-piece computer displays in front of his face, both of which present serious safety issues.